The field of the invention is stabilized platforms and systems for cameras. More specifically, the invention relates to gyroscopic stabilization systems for motion picture and video cameras.
In motion picture, television or video filming or recording, the camera is often supported on a vehicle, to follow an action or moving sequence to achieve a desired camera angle or effect, or to film occupants in or on the vehicle. Various specialized camera cars, camera trucks, cranes, and dollys have been used for this purpose. In addition, specialized camera support systems have been used to mount cameras on aircraft such as airplanes and helicopters, and on watercraft, such as boats, floats, or buoys.
In filming or recording with motion picture or television or video cameras, it is important for the camera to be maintained in a stable position. In the most basic form, camera stability has been achieved by mounting the camera on a tri-pod. However, when the camera itself is mounted on and moves with a vehicle, maintaining camera stability often becomes difficult. For example, with a camera mounted on a camera car moving along a roadway and filming or recording a fixed subject on the ground, e.g., a building, or a subject which is also moving e.g., another moving vehicle, the camera and the lens of the camera will necessarily move in unintended and undesirable ways, due to various factors. These factors may include changes in the roadway direction or inclination, changes in the vehicle orientation, due to shifting gravitational or inertial loads, as well as for other reasons. Undesirable movement can be especially problematic when the camera is mounted on an aircraft, where movement readily occurs along three dimensions, and where wind buffeting of the camera can be extreme. The undesirable camera lens movement resulting from these factors reduces the quality of the filmed or recorded images, by causing the images to be improperly framed, or to appear jumpy or erratic.
Production time can be extremely expensive. Even relatively short, simple film or video sequences, such as a scene in a motion picture or television production, or a TV commercial, generally requires large numbers of film or video production professionals, such as directors, actors, camera crew, grips, lighting and sound personnel, prop, background set, make-up and wardrobe personnel, etc. Consequently, even the loss of one minute of production time can translate into hundreds or thousands of dollars in increased production costs. If special effects, stunts, large numbers of extras, animal actors, etc. are involved, costs can be even higher. Accordingly, any techniques that avoid delays in filming or re-shooting, are very advantageous.
To maintain the camera lens in a stable position in these types of situations, various camera stabilization systems have been proposed. Generally, these camera stabilization systems rely on gyrostabilization and feedback techniques which detect unintended or undesirable movement of the camera, and then compensate for that movement via motors driving the camera platform. The term gyrostabilization here means any camera movement compensation system using position, rate, or acceleration sensors, whether “gyroscopic” or of another type.
While these types of stabilization systems have been successfully used in the past, various disadvantages remain. The gimbal system used in existing stabilized camera systems, which allows the camera to pivot about three perpendicular directions, are often large and relatively time consuming or difficult to balance. This can restrict camera movement and positioning and also make transport, installation and set-up (including balancing) more difficult. Moreover, existing systems generally have large moments of inertia, making them relatively slower in responding to correction forces applied by the motors. Accordingly, there is a need for a camera stabilization system which is compact, lightweight, and agile in responding to correction signals and forces.
The camera operator, cinematographer, or director will often want to manually aim the camera, by simply grabbing the camera with the hands, and aiming it as desired. Existing camera stabilization systems, when turned on, will automatically resist such manual movement. While this resistance can be overcome by applying force sufficient to overcome the torque limits of the motors in the stabilization system, this results in jerky and imprecise camera movement. As a result, manually aiming or positioning of the camera by forcibly overriding stabilization system has disadvantages, and generally is almost never acceptable during filming. On the other hand, turning the stabilization system off to perform hand or manual camera aiming or movement results in loss of all stabilization functions. With the stabilization turned off, the only forces holding the camera in position are the frictional forces in the various rotation joints. Based on the weight of the camera and other factors, these frictional forces may be insufficient to even hold the camera at any desired position. In addition, due to static and dynamic friction characteristics, achieving smooth and accurate camera movement, even with the stabilization system turned off, can be difficult or impossible. Accordingly, there is a need for a camera stabilization system which allows for smooth and accurate manual aiming.
Over longer periods of time, drift in existing camera stabilization systems can cause the camera to become improperly positioned. The severity of drift varies with the accuracy of the sensors in the system. Due to drift, under certain conditions, the camera may require repositioning before filming or recording is continued after a lunch break or other pause. This can result in delays and added production costs. Accordingly, there is a need for a camera stabilization system which compensates for or eliminates drift.
Existing camera stabilization systems have various other disadvantages as well, relating to backlash in the drive systems, balancing, large moments of inertia, controls and accuracy of positioning. Accordingly, various engineering challenges remain in designing an improved camera stabilization system.